Know Yourself First

The third chapter of The Art of War ends with its most famous saying. In Lionel Giles’s 1910 translation: “If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”

The Chinese is 知彼知己者，百战不殆；不知彼而知己，一胜一负；不知彼，不知己，每战必殆.

Two things in this line are easy to miss. The first is a word. 殆 means “danger.” So 百战不殆 means “not in danger in a hundred battles.” It does not promise a hundred victories, though people often quote it as 百战百胜, “a hundred battles, a hundred wins.” In fact, the same chapter says 百战百胜 is not the best result. Giles translates it: “to fight and conquer in all your battles is not supreme excellence.” Knowing both sides keeps you out of danger. It does not guarantee you win.

The second thing is a count. There are two kinds of knowledge, about the enemy and about yourself, so there are four possible cases. Know both. Know yourself only. Know neither. And know the enemy only. Sun Tzu gives a result for the first three. He never mentions the fourth.

I teach engineering, and in my field a missing case in a table is usually a bug. But here I think it may be a point. What if Sun Tzu leaves out the fourth case because it cannot happen? What if you cannot really know the enemy unless you first know yourself?

Philosophy of mind gives one reason this could be true. In 1986, the philosopher Robert Gordon argued in the journal Mind and Language that we often understand other people by simulation. To predict what someone will do, we imagine ourselves in their situation and use our own mind as the model. This idea is now called simulation theory. If it is right, my picture of the enemy is built partly out of my picture of myself. So if I do not know myself well, including the ways I differ from other people, I will copy my own habits into my picture of him.

Psychology has evidence for this kind of error. In 1977, Lee Ross, David Greene, and Pamela House asked Stanford students to walk around campus for thirty minutes wearing a sign that said “Eat at Joe’s.” About half agreed, and half refused. Then each student guessed how many other students would make the same choice. The students who agreed thought most others would agree too. The students who refused thought most others would refuse. Both groups used themselves as the model for everyone else. Ross and his colleagues called this the “false consensus effect.” Notice what the students got wrong. They knew their own choice perfectly well. What they did not know was how unusual it might be.

An engineer would call this a calibration problem. If the reference you measure against is wrong, every measurement you make with it is wrong in the same direction. Knowing yourself is the calibration step: learning where your own view sits, so you can correct for it. Without it, studying the enemy carefully does not help, because you are measuring him with an instrument you have never checked.

This is my reading, not the text’s, and it stretches one word. In Sun Tzu, 知己 means knowing your own side: your army, its strength, its supplies, its readiness. I am extending it to the general’s own mind, which plays the same role when he pictures the enemy. Sun Tzu also does not say why the fourth case is missing, and the classical commentators offer another explanation. Zhang Yu, quoted in Giles’s notes, says that “knowing the enemy enables you to take the offensive, knowing yourself enables you to stand on the defensive.” On his reading, the two kinds of knowledge do different jobs, and nothing is missing. That is a fair reading too.

But the simulation reading fits one detail well. The only partial success Sun Tzu allows is the case where you know yourself. Knowing yourself alone still wins half the time. Knowing the enemy alone is never offered at all. Read this way, the saying is also a short lesson on the problem of other minds. We have no direct view into another person’s mind, so we use the one mind we can see from the inside, our own. That makes self-knowledge the first step in reading anyone else, including an enemy.

Editor’s note: you can try the 1977 sign study yourself. Would You Wear the Sign? asks for your choice and your guess about everyone else, then compares them with the original results and with this site’s readers.